The invention relates to a vehicle data bus system having a location determining arrangement that includes a locating computing unit and a locating sensor system having at least one GPS (Global Positioning System) receiver with associated GPS antenna and gyro data acquisition means, the data bus system also having a plurality of bus users connected to a data bus, for data transmission to one another.
European patent document EP 789 343 A1 discloses a vehicle data bus system of the generic type, having locating means and a plurality of connected bus users. GPS receivers, gyro data sensors, wheel speed sensors, tachometers, odometers and acceleration sensors can be used as locating sensor systems. A locating computing unit uses the data of the locating sensor system to determine the position data which can be output onto the data bus.
Motor vehicles of advanced design frequently include position determining devices that operate on the basis of the GPS, and when necessary, the latter are supported by further position-determining devices for compound navigation (for example, a gyroscope and an odometer). In addition, a plurality of vehicle-mounted components, (conventionally control devices referred to herein as xe2x80x9cbus usersxe2x80x9d, for performing local vehicle-mounted control functions), are frequently connected to one another via a data bus which can be part of an entire data bus network.
Recently, telematics service units are also becoming significant bus users. Such telematics service units have a communications connection, on the one hand, to the xe2x80x9cvehicle worldxe2x80x9d via the vehicle data bus and, on the other hand, to remote stations, which are external to the vehicle, via one or more wireless transmission channels. They may be used for example, to perform functions such as emergency calls, pursuit of thieves, determination of traffic situation data of sample vehicles etc.
In earlier motor vehicles of this type, the locating devices on the one hand and the data bus with connected vehicle control devices on the other hand formed separate vehicle subsystems, and frequently only one of the two was implemented. The locating devices themselves were frequently composed of a relatively large number of individual components. U.S. Pat. No. 5,644,317 for example, discloses an automatic vehicle locating system having a locating sensor system composed of a plurality of individual sensor units, and a locating computing unit which receives output signals of the various locating sensor units. The locating computing unit outputs data relating to the vehicle position and vehicle situation to an external unit via a wireless communications channel for presentation of the transmitted position/situation data.
A vehicle-position-determining system disclosed in U.S. Pat. No. 5,740,049 determines a first temporary position information item by reference to the output signals of a vehicle speed sensor and a gyroscope, and corrects it by deriving a second temporary position information item by reconciliation with stored route data. A third temporary position information item is acquired from the output signal of a GPS receiver. By evaluating or reconciling the various temporary position information items, a definitive vehicle position is determined and displayed on a screen in a road map view.
The locating devices are often an integrated component connected upstream of a vehicle navigation unit, for the sole purpose of supplying position and situation data (i.e., orientation of the vehicle in space) data for navigation and/or for visually displaying determined position or situation of the vehicle. See, for example, European patent document EP 0 675 341 A1 and International patent document WO 98/36288 A1.
International patent document WO 98/10246 A1 discloses a device for recording geographic data which, depending on the configuration, can be determined as a portable device or for installation in a vehicle, for example, and has not only position-determining means but also video cameras for recording images. A computer unit receives the data output by the positioning-determining means and the video cameras and evaluates it to determine the direction of the image relative to the device, or the geographic data for an object sensed with the camera. The device can have a communications connection via a wireless communications channel to a remote station, for example a central processor unit there.
German patent document DE 196 40 735 A1 discloses a telematics device for a motor vehicle, which includes a car radio with an RDS module and a built-in locating system with GPS module, a radio telephone with GSM module, a memory and a display. The RDS module, the GPS module and the GSM module are installed together with a voice unit and the car radio in a housing of the telematics device. The housing has antenna terminals for at least the car radio, the GSM module and the GPS module as well as interfaces for at least one CAN bus and/or one further data bus as well as for at least one loudspeaker and/or a microphone. By means of travel sensors (for example wheel sensors, a direction sensor and/or the GPS modules the position of the vehicle can also be connected and output on a digital map of the visual display. By communicating with a control center or a navigation system which is built into the telematics device or a navigation module which can be connected thereto via the CAN bus or the further data bus, it is possible to calculate a desired travel route which is then displayed on the visual display. Via the CAN bus and/or the further data bus, the telematics device can influence an engine control unit which forms a further bus user.
One object of the invention is to provide a vehicle data bus system of the type described above which is flexible and convenient to use, and can be satisfactorily standardized.
This and other objects and advantages are achieved by the vehicle data bus system according to the invention, in which a locating module is embodied in a specific way as one of the bus users connected to the data bus. Components of the locating module which are used for locating the vehicle are integrated primarily into a single structural unit. The associated locating sensor system is at least partially integrated into the locating module and also connected to the data bus so that the locating module acquires at least part of the necessary locating sensor data internally, and also receives it via the data bus. Specifically, the locating module contains a locating computing unit, which performs the computational determination of a position, and a GPS receiver. In addition, it has a gyroscope or means for receiving corresponding gyro data via the data bus from a travel dynamics/traction control system if the latter comprises the respective gyro data acquisition sensor system (as, for example, in some conventional travel dynamics control systems).
As a result of the modular combination and the data bus connection of the locating apparatus, they can be standardized for use in different vehicles (and in different countries) without extensive adaptation measures, and can provide appropriate locating information on the data bus in a flexible way according to need, from which data bus users. The locating information which is thus made available comprises, in particular, vehicle position data, direction of travel angle data, travel speed data and altitude data (data on the instantaneous altitude position of the vehicle above sea level) (NN). In a preferred embodiment of the invention, a locating precision classification (location quality) is also provided in the form of an identifier which indicates the degree of unreliability of the calculated position data.
In order to determine the locating information, the locating module uses not only the gyro data and the GPS data, but also wheel speed data and data indicating whether the vehicle is driving forward or backward at a given time, which it obtains from the data bus. The locating information can be used, in particular for vehicle control units which perform various vehicle-related functions, such as travel dynamics control, anti-lock brake control, traction control, engine control and gearbox control, by display instruments such as a combination instrument or by a specific comfort information display, and also by communication units which communicate with vehicle-mounted components via the data bus and with remote components, external to the vehicle, via a wireless communications channel.
In another embodiment of the vehicle data bus system according to the invention, the structural unit which represents the locating module also contains an integrated GPS antenna so that it is unnecessary to mount a separate GPS antenna on the vehicle or to connect it to the locating module.
In still another embodiment of the invention, a navigation unit, which receives the position data from the locating module, is provided as a further bus user. By means of a conventional map-matching process in which this position data is compared with stored travel network data, it acquires improved position information with a new location position classification (location quality). The navigation unit characteristically feeds back the corresponding position correction data via the data bus to the locating module which can use said data for precision-improving correction reconciliation.
In yet another embodiment of the invention, one or more telematics service units are provided as further bus users, which use the locating data acquired from the locating module (for example for an emergency call function) to pursue thieves and/or to determine traffic situations using sample vehicles (what is referred to as a floating car data method).
According to another embodiment of the invention, an engine and/or a gearbox control unit, provided as a further bus user, utilizes the data bus connection, inter alia, to read in the altitude position data made available by the locating module. As a result, it is possible to dispense with an altitude sensor which is conventionally present in modern units of this type.
Finally, according to another feature of the invention, the locating module is part of a further bus user, which uses the locating computing unit for additional tasks.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.